There are a number of eavestroughing systems manufactured by Plasmo, Genova and GSW which use an extruded plastic eavestrough section in combination with hangers of different arrangements for supporting of the eavestrough from a fascia. Many of these systems use what is referred to as a "hidden" hook, that is the hook is hidden by the eavestrough and essentially supports the eavestrough either side thereof at the front and rear surfaces.
Our earlier system utilized an injection molded eavestrough hook having a central port in an upper edge used to secure the hook to the fascia. Once the hooks were installed on the fascia, the eavestrough section was suspended from an outer edge of the hook and the eavestrough section was rotated about the front of the hook, such that the rear of the eavestrough section came into engagement with a rear portion of the hanger and resulted in a snap type fit at the rear edge of the hanger. Details of this system are shown in U.S. Pat. Nos. 4,257,716, 4,632,342 and 4,901,954. With this arrangement, the eavestrough sections were supported by the eavestrough hangers at the front and rear edges and the bottom portion of the eavestrough was free of obstruction from the hangers. Other systems use a bottom support hanger, which is basically a "U" type bracket, however, these have not proven popular due to the interruption of the bottom surface of the eavestrough sections.
The use of hidden hooks attached to the fascia and the various arrangements for securing the eavestrough to the secured hangers resulted in a system which required much of the assembly to be carried out at the elevation of the fascia.
A further problem experienced with these eavestrough systems is with respect to high shock loads which can occur during winter conditions. It is possible for the eavestrough sections to fill with ice, with ice on the roof also being partially supported by the eavestrough section. This can result in high stress loads on the hangers and the hangers have been known to fail. It can be appreciated that the characteristics of the plastic change with temperature and this high load demand and cold ambient temperatures leads to a condition where the hangers can fail. Failure of one hanger creates somewhat of a domino effect, as the other hangers have to pick up the additional weight, and these too can fail.
Another winter condition which is even more of a problem is the possibility of snow or ice on the roof melting and sliding off the roof and impacting upon the eavestrough system. This is of a particular problem with metal roofs where often the snow and ice on the roof slides off and creates extremely high shock loads on the eavestrough system. This has been known to essentially strip the eavestrough system from the fascia by either ripping of the hangers directly from the fascia or causing the hangers to fail, generally adjacent the fascia.
Eavestrough hangers of what is referred to as the hidden hook design typically have a base and some sort of cantilevered "I" or "T" beam projection for engaging the front edge of the eavestrough and engaging the rear edge of the eavestrough. Therefore, the cantilevered portion has been designed to be stiff and to provide positive securement adjacent the base of the hanger. This desire to provide a rigid type hanger causes problems during the high loads discussed above.
The present invention defines an eavestroughing system which is easier to install and also defines an improved hanger.